This invention relates to concrete highways or roadways, and more particularly to an improved, long-lasting cover for highway expansion joints, and a method for installing such covers between adjacent concrete slabs of a road or highway.
It has long been customary to form modern highways, and associated bridges and overpasses, from concrete slabs, which are poured one after the other along the length of the proposed highway or overpass to form a firm roadbed. Since concrete tends to contract and expand in response to falling and rising temperatures, respectively, it also has long been customary to interpose between the confronting ends of adjacent slabs resilient expansion joints. Such joints permit the slabs to expand and contract without unduly distorting the horizontal surface of the roadway; and they also prevent debris and water from entering the spaces between adjacent slabs. In the case of overpasses such joints prevent water and debris from dropping onto traffic passing beneath an overpass; and in the case of conventional roadways they prevent ice from forming between adjacent slabs and possibly interfering with the normal expansion and contraction of the slabs.
Among the solutions heretofore proposed, U.S. Pat. No. 4,080,086 suggests using elongated anchor pads, which are secured by studs and nuts to the upper surfaces of adjacent concrete slabs at the confronting ends thereof. These pads are connected to opposite sides of a flexible or resilient sealing member, which is thus supported by the anchor pads sealingly between the adjacent slabs. The disadvantage of this apparatus is that it requires a considerable amount of manual operations for bolting or mechanically securing the anchor pads to the concrete slabs.
In the structure taught by U.S. Pat. No. 4,285,612, a silica-epoxy mortar material is poured and tamped into confronting, notches or recesses formed in the confronting surfaces of adjacent slabs, and is allowed to set. Thereafter an elongate, resilient seal is inserted into the space between the strips of mortar, and a filler material is pumped into a bore in the center of the seal thus forcing the seal to expand outwardly into sealing engagement with the confronting edges of the now-cured mortar strips. With this construction, however, water or moisture is prevented from entering the space between the slabs only so long as the sides of the resilient seal remain sealingly engaged with the confronting surfaces of the strips of mortar.
The U.S. Pat. No. 4,098,047 teaches the use of an elongate, resilient, tubular seal having laterally extending side flanges, which are secured by a grouting material in opposed, longitudinally extending recesses formed in the confronting ends of a pair of adjacent concrete slabs. The tubular seal itself, however, remains exposed to the elements. U.S. Pat. No. 4,295,311 illustrates a somewhat similar expansion joint, but the latter joint is prefabricated all in one piece, and is then adhered by a plastic in confronting recesses formed in the adjacent concrete slabs.
U.S. Pat. No. 4,601,604 discloses a method of covering a resilient expansion joint or seal by pouring thereover a polyurethane layer, placing an extruded, plastic core over this layer, and then covering the core with still another layer of plastic, such as a fluid-polymer. At least two layers are thus poured over the resilient expansion joint after the latter has been inserted between the confronting surfaces of adjacent slabs. Instead of using a resilient seal between the confronting surfaces of adjacent slabs, U.S. Pat. No. 4,279,533 suggests securing a steel plate over the gap between the adjacent slabs, and then securing the plate in place with a plastic material.
Despite all the efforts heretofore made to provide a satisfactory traffic bearing seal between the confronting surfaces of adjacent concrete slabs, prior such products have not proved to be successful after being in use for relatively short periods of time. Traffic driving over the joint breaks down the upper, confronting edges of adjacent slabs. The breakdown progresses until the joint fails and requires major repairs. Moreover, prior such seals have required, more often than not, considerable work on the seam between slabs after the slabs have been poured.
It is object of the invention, therefore, to provide an improved expansion joint of the type described, which utilizes a novel cover means for covering and protecting the resilient seal, which is interposed between adjacent ends of two slabs to allow expansion and contraction thereof.
Another object of this invention is to provide an improved expansion joint cover of the type described which protects the upper edges of adjacent slabs at the intersections of the horizontal and vertical end surfaces of the slabs, thereby preventing traffic from breaking down such edges.
A further object of this invention is to provide an improved expansion joint cover of the type described which makes use of a number of preformed or precast elements, thus minimizing the time and effort required to install the cover during roadway formation.
Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawing.